Problem for me, puzzle for you. Any Ideas?

[F-22 Raptor SHO]

Ok guys, this one has me stumped. I provide every detail I can think of, so it is a bit long.

95 ATX. 86,000 miles. All up to date on Maintenance. Ted LPM. Car kicks butt as it always has.

Last year (October) I moved from Michigan to AZ. Car was in airport parking lot in the AZ valley for 1 weeks (read: 100 deg heat). Upon returning from the airport with a full trunk and family in tow 40 miles into the 120 mile trip up the mountain, the car quit: stumbling, dying, choking, pulled off the side of the road.

IRCM was making a clicking noise with ignition on, it would crank, but wouldn’t stay running (more choking and dying). Code read was 511 (No power to PCM pin 1 or bad PCM processor. No other codes. Now typically this would be a code all the experts would say "hey its the lpm". I got it towed and of course the car ran fine when we reached our destination 100 miles away which by this time, it was a cool evening and the car cooled down.

I still suspected the PCM might be bad (or that pin 1 was having problems). I disconnected the harness and examined and reattached it, checked the LPM connection that seemed fine. Problem resurfaced a few days later during city driving (modest temperature. I wiggled the PCM while in the left turn lane and it came back to life. So later I secured the PCM and all was well.

Fast forward to last Friday: Returning from airport with family and full luggage, full cabin, it quit in the same way (in rush hour of course). Temp was not outlandish: running on M with new rad and dex cool. Only code was the 511. No IRCM box clicking. Wiggle PCM trick didnt work, disconnect and reconnect harness didnt work. Off Road SHO came with another computer (93 ATX X2J). We swapped it in. Car ran perfect. Ran codes to be sure, all was ok. Ok, bad computer. Figure I own Tom a computer and a steak dinner. Came home up the mountain (evening 60 deg by now). Car ran fine.

Ok, yesterday was returning from Sedona, (25 miles up a switchback mountain road (3000 foot altitude change), car quit again with the same stumbling and dying (still had Tom’s X2J computer with no LPM) If I waited, the car would start again, but die within 1/4 mile. No CE light, thrown but there were 4 codes pulled, but I was having problems running the KOER test correctly which later I thought I was able to remedy by Goosing the gas after o/d button was turned on and off. Codes were:

129 - No MAP or Mass Air Flow sensor change during "goose" test

167 - 167 No Throttle Position sensor change in "goose" test (must get at least 25% rotation)

225 - Knock sensor not tested (ignore if not pinging)

632 - Transmission Control Switch (TCS) (OD button) should be cycled once between engine ID and Goose test.

Nursed car home to garage and let it cool down.

Votage to TPS and MAF was fine.
For grins I yanked off the maf and tps then started the car, I was able to reproduce the problem only one brief time out of 5 attempts but it gave me a CE light immediately. I did observe that the MAF plug wasn’t as secure at it could have been, (clip wasn’t all the way clipped, but recall, at the airport I got no TPS or MAF code). Car ran fine.

I did think the heat on the DIS could have been a potential cause as 1: the dis was a swap out when I thought it was going bad 2 years ago, I never put the original back on, and 2 I never did use heat sink compound, rather I used dielectric grease. I put my original DIS back in last night, used liberal amounts of radio shack heat sink compound and put it all back together. Reset computer and idle.
Only facts that seem to be constant are:

Happens when car is under moutainous driving on hot days
511 code is thrown
Problem is sudden with no warning.
PCM wiggle seemed to help once, but not any more.
Chip is not on second computer, so I dont think that was the problem.

There is only one way to see if I get the problem again and that is to put my family in danger by driving up the mountains with a full load.

Any suggestions?

I am going to recheck ground wires today, and check the power supply to the PCM.

 

[projectSHO89]

When in "failure mode", does the CEL illuminate at full brightness or is it dimmer than normal?

Have you been able to isolate the source of the problem to the correct subsystem - Air, fuel, or spark?

Steve

 

[F-22 Raptor SHO]

In failure mode, if I did see the CE light only for a second as the motor died, it was standard intensity. At least thats the best of my recollection.

As to which system: I did not check spark or fuel on the side of the road. The car did start though just choke alot before dying. Makes me think spark is at least present.

During dying mode, the engine revs slowly went down as my foot was to the floor.

Im trying not to chase rabbit holes here as the codes first pulled led me to believe there was a real problem with TPS or MAF but again, I didnt think I ran the test right during dynamic response those initial times.

Mind you I did not get any fuel pump codes or trouble signs, however, I did note that when the car was running right in my garage, I personally thought the whine of the fuel pump motor was especially higher than the normal hummmmm (more like a high pitched tone, not a scream or gurgle, or shimmy sound, just a ringing in the ears sound). Note: original fuel pump. I dont want to get to chasing ghosts on this one if it is not clear that the pump is bad.

I am going to confirm the condition of the Pin 1 harness wire (corrosion, looseness, and condidtion, but am skeptical as the x2j computer didnt give me a 511 at all.

 

[sdpatt]

That sounds like a heat-related failure of the fuel pump. After the car dies and you turn the ignition key to ON and hear the ICRM click, do you hear the fuel pump run for 1.5 seconds? If a click, but no pump, the fuel pump is the suspect. At this point I recommend the 155lph or 190lph Walbro pumps since the extra capacity provides a much longer service life.

 

[93EmeraldMTX]

you're running dex-cool?

 

[93EmeraldMTX]

you're running dex-cool?

 

[F-22 Raptor SHO]

My mind may have not been focussed enough at that time to listen for the pump, or it may have been very weak sounding for me to notice.

I did run a test on the way home from lunch, I cut the ignition while driving down the road (no worries, it was an isolated straightaway), the feel of the car when the ignition was cut was now where near the sound the car made when it quit yesterday. Yesterday it was a slow death, gradually down to nothing, whereas today when I shut er down, it was an immediate cutout and coast to the side. Even yesterday when it did come back to life temporarily, I could mash it to the floor and it would fight to get up to speed....Makes sense if it were fuel starved.

Of course the car runs fine now and the pump sounds normal, but then again, I'm not out in the middle of nowhere.

I will search the forum for fuel pump maladies and see how some of the symptoms are worded.

Oh, and yes, I run dex cool. I dont like flushing radiators every spring. 5 years is much more to my liking...besides that, it was the same price as the green stuff at walmart for Prestone.

 

[sdpatt]

I run Dex-Cool with the benefit of extended life of the coolant and the water pump seals. All you need is a thorough flush before "oranging" your system.

 

[projectSHO89]

Next time it chokes, pop the gas cap and listen for a whoosh of air going into the tank. If so, replace your gas cap.

Steve

 

[F-22 Raptor SHO]

Update:

Taking SDPATT's fuel pump suggestion, I have ordered up a Walbro 190lph pump....a good thing to have around anyways just in case, so regardless if this is the issue.

I used my tire pressure gauge to check fuel pressure from the schrader valve. Mind you the car is running fine now, so I dont expect any problems. The pressure reads 30 psi at idle and 40 psi at 3950 (rev limiter hits at 4000).

At idle with the fuel pressure regulator hose removed and plugged with my finger, pressure reads 40 psi.

Key On Engine Off, the 1.5 second burst puts pressure at 40 psi with fuel pressure regulator hose intact.

Guess I will need to see what happens to fuel pressure when it runs pissy again.

 

[projectSHO89]

Well, if it's any consolation, your readings are perfect for a working fuel delivery system!

Steve

 

[AutoSHO]

That is a very unusual problem indeed.

How old is the CPS, out of curiousity?

 

[Huntervf]

Not too old IIRC, swapped out last year at 70,*** right Mike?

What you're describing does now sound like a fuel problem...choking, gasping, dying slowly. Maybe you were right all along, maybe 1.5 years ago when you pulled into my driveway and said "hey does that whine from the rear of the car sound normal to you?" you were on to something.

Have you tried reinstalling your DU41 and LPM yet?

 

[RStalveyARFF]

are you sure you installed an X2J? Cuz that's an MTX computer....

<small>[ March 16, 2004, 01:30 AM: Message edited by: SHO91MTX ]</small>

 

[TwiceSHOwn]

Reading your story was like listening to myself 2 years ago.

Hot day (100+) at 8000 ft eleveation in arizona.

Car did EXACTLY what you described same codes..everything.

Bad fuel pump...almost like vapor lock.

Replaced the pump with 155 unit.

I dont have the problem anymore.

 

[DHMag]

some of the early Gen1s were known to have a loud fuel pump whine. mine had it(til i replaced with a 190), my moms 86 LX had it.

 

[F-22 Raptor SHO]

Yea Huntervf and I did the whole 60k about 20k ago. Back then it was a bad CPS that threw a code which triggered a response from the SHO/SVT Kalamazoo troubleshooting team.

Tom and I are investigating various aspects to see what may be misbehaving, but the key in all the quit situations is that it will start, just choke at 500RPM and not move. CPS gives a tach response. Tom is suggesting that a possible fuel pressure regulator problem might exist which could simulate the same problem. I have my fuel pressure gauge with me now so I can check it when it happens again.


The swap computer is out of a 93 ATX. H2Z now that I am recalling. I had just purchased an X2J for my 90 a few days before so I had X2J on the mind.

I am noticing these past 2 mornings that it starts kinda hard. It sometimes needs some help by pressing the accelerator down a bit. Sometimes it tends to die once when I put it in reverse. Hmmmmm...

My wife thinks the car just doesnt like leaving the city as I dont get any issues around town.

Havent put my D4U1 back in yet. Speaking of that computer, what is it about the D4U1 that everyone likes? I hear you all saying it is a better comptuer...why?


Meanwhile, I drive the "ol' unreliable" 95 ATX, while my wife is spinning around town with the inlaws in the 90 MTX, which by the way looks great since the new paint job. They are going to the Grand Canyon today in it (2 1/2 hour round trip)....told the wife not to let pops drive it quite yet.... eek! It's just a car, but funny how they tend to grow on you.

I will keep you posted.

 

[Huntervf]

Mike, do you remember Steve Wilcox (aka "burnout")? His 93 MTX had a bad FPR and it developed a fluxuating idle, bobbing up and down more and more until it would finally die. Never had problems while driving though except he'd get a CE light that set no codes (which I didn't think was possible until I saw the CE light myself and checked for codes only to find none).

Not sure if that's the ONLY symptoms of a bad FPR, but it was at least one symptom.

 

[RStalveyARFF]

Ted B won't program the LPM for the 93 ATX comp so that's why many switch to the 94/95 computer.

 

[F-22 Raptor SHO]

Yea I remember that day the fuel pump was squealing and think about it often during start up. Thinking one day I will need to replace it. That day in your drive was about the time Scott and I did the pump in his SC.

Yea, good old Burn out.....a FPR is the least of his worries now.....man did he drive that SHO hard from the Sec of State lot that night....funny he blew the diff like a week later. 3.2 MTX with no quaife will do that.

Nice car though.